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8

Troubleshooting

If you think your subwoofer has a problem, please do everything you can to confirm the problem before contacting us for service,

including reading through the troubleshooting section. Many times the problem actually is caused by other items in the system or the

subwoofer’s interaction with those items. Much of the time, the service department will not be able to reproduce the error.

Problem

Cause

Solution

Humming or 

buzzing noise

Subwoofer goes into 

STANDBY mode 

while material is 

playing.

No  output  from  the

subwoofer (the LED

does not light up).

You have an amplifier problem.

Your speaker wires or interconnects are

the cause.

A light dimmer or other triac based (SRC)

device is on the same AC circuit.

You have a problem with other equipment.

The source is not providing enough signal.

AC power is not getting to the amplifier.

The amplifier’s fuse is blown.

The amplifier has gone into 

self-protect mode.

•  Disconnect all interconnects from the amplifier. If still 

hums, call/email technical support.

•  It is possible that some cables have a poor or broken

ground due to poor construction, oxidation, or damage.

Also,  poorly  shielded  cables  can  potentially  pick  up 

noise. Try another interconnect or speaker wire. Also, 

move  the  signal  cable  away  from  AC  cables,  power 

transformers, or other EMI sources.

•  Use an AC line filter or plug the unit into a different circuit.

•  If hum goes away when interconnects are disconnected,

the  hum  is  coming  from  the  rest  of  your  equipment. 

Add them back one piece at a time. The one that causes

the system to hum is the source of the hum.

•  The unit is going into STANDBY mode during the quiet

passages. Try turning the source signal up. On a Dolby 

Digital receiver, turn the SUBWOOFER level up in the 

SPEAKER SET-UP menu. After you turn the signal up, turn 

down the volume knob on the subwoofer to compensate.

•  An alternative is to turn the subwoofer ON/AUTO/OFF 

switch  to  the  ON position.  It  does  not  use  any  more 

power and does not affect reliability.

•  Check that the power cord is plugged in securely at both

ends and make sure that the power outlet the subwoofer 

is plugged into is working.

•  Check the fuse. The fuse is located on the amplifier, near

the power plug. Unplug the power cord and remove the

fuse holder with a flat head screwdriver. If the fuse is

blown,  the  output  transistors  are  probably  damaged.

Call/e-mail technical support for authorization to send 

the amplifier back for service.

•  Unplug the power cord. Wait 2-3 minutes. Plug the power 

cord back in. It should power up and work normally.

Summary of Contents for ULS-15

Page 1: ...ze the ultra low distortion ultra high output capability of the woofer This amplifier is capable of delivering up to 1000 W rms short term power Great Connectivity Now included are more connectivity options than any other subwoofer we know of at any price Inputs include balanced XLR unbalanced RCA wireless and speaker level This flexibility allows you to use the subwoofer in recording studios high...

Page 2: ...ly at plugs convenience receptacles and the point where they exit from the apparatus 11 Unplug this apparatus during lightning storms or when unused for long periods of time 12 Refer all servicing to qualified service personnel Servicing is required when the apparatus has been damaged in any way such as power supply cord or plug is damaged liquid has been spilled or objects have fallen into the ap...

Page 3: ...bwoofer at least 2 ft away from computers in order to prevent the hard drive from being erased Rules of thumb for placement Avoid the center of the room In general avoid placing the subwoofer half way between the front and back walls You should avoid sitting in the middle as well Use near field placement You get the tightest upper bass and the most punch if you can place the subwoofer close to you...

Page 4: ... other choice Integrated amplifiers or stereo receivers with no pre outs fall in this category The subwoofer will operate in bass augmentation mode i e the main speakers will be running full range You dial in the subwoofer to come in just where the main speakers start to fade out Since the subwoofer uses its own amplifier and has a high input impedance it will not alter the loading on your main am...

Page 5: ... automatically go into STANDBY mode Crossover Defeat Switch If you are using a SUBWOOFER or LFE output you can disengage the crossover by switching it to OUT The crossover should be switched to IN when using high level inputs or two channel low level inputs Crossover Frequency Control This low pass crossover controls what frequencies are handled by the subwoofer ULF Trim This compensates for room ...

Page 6: ...r than for music 3 dB higher is a good choice if your receiver allows you to set levels for each source Step 5 Crossover If your controller has bass management and has a steep crossover slope set the crossover switch on the subwoofer to Out If your controller has a gentle crossover slope 12 dB Oct or less set the crossover switch on the subwoofer to In and set the crossover fre quency knob on the ...

Page 7: ...level down 5 dB 7 If your controller has a subwoofer out level use this to adjust the level If it does not play the 50 Hz tone and adjust the subwoofer volume control to get the desired change in level If you are using the Radio Shack SPL meter compensate for the meter s deep bass deficiency The older analog Radio Shack meters are down 12 dB at 16 Hz 7 dB at 20 Hz 4 dB at 25 Hz and about 2 dB down...

Page 8: ...pick up noise Try another interconnect or speaker wire Also move the signal cable away from AC cables power transformers or other EMI sources Use an AC line filter or plug the unit into a different circuit If hum goes away when interconnects are disconnected the hum is coming from the rest of your equipment Add them back one piece at a time The one that causes the system to hum is the source of th...

Page 9: ...reless Make sure the channel selection are the same on the trans mitter and receiver Check and see if the led above the Wireless Wired switch is lit up solid green If not move the antenna transmitter and subwoofer to get better reception If you are using the wired con nection make sure the Wired Wireless switch is set to Wired With the volume on the subwoofer turned to a low setting try plugging t...

Page 10: ... states do not allow limitations on how long an implied warranty lasts and or do not allow the exclusion or limitation of incidental or consequential damages so the above limi tations and exclusions may not apply This Warranty Does Not Cover Damage caused by abuse accident mis use negligence or improper operation Products that have been altered or modified Any product whose serial number has been ...

Page 11: ...11 Notes ...

Page 12: ...12 HSU Research 985 N Shepard St Anaheim CA 92806 1 800 554 0150 HSURESEARCH COM ...

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